ISSN 1392-3196
Žemdirbystė=Agriculture
Vol. 99, No. 4 (2012)
371
ISSN 1392-3196
Žemdirbystė=Agriculture, vol. 99, No. 4 (2012), p. 371–378
UDK 633.15:631.348.45
The effects of drift-reducing nozzles on herbicide efficacy
and maize (Zea mays L.) yield
Mario LEŠNIK, Branko KRAMBERGER, Stanislav VAJS
University of Maribor, Faculty of Agriculture and Life Sciences
Pivola 10, SI-2311 Hoče, Slovenia
E-mail: [email protected]
Abstract
Field trials were carried out in 2009–2011 to compare the performance of herbicides for weed control in maize
(Zea mays L.). Herbicides were applied by standard (API, “Albuz”) and by drift-reducing (AVI, “Albuz”) nozzles.
Mixtures of herbicides based on 2,4-D, bentazon and foramsulfuron were applied post-emergence with a tractor
mounted field boom sprayer at a spray volume of 150 or 300 l ha-1 in the form of droplets of different size classes
(volume median diameter (VMD) from 100 to 800 µm). The main weed species in the field trials were: Ambrosia
artemisiifolia, Amaranthus retroflexus, Chenopodium album, Convolvulus arvensis, Elytrigia repens, Echinochloa
crus-galii, Polygonum lapathifolium and Fallopia convolvulus. The efficacy (%) of herbicides and maize yield
were assessed. The impact of the studied factors on herbicide efficacy against broad-leaved weed species differed
from that against narrow-leaved species. In comparison to the standard API nozzles, the overall efficacy of driftreducing AVI nozzles was lower in 8 of 12 herbicide applications. The efficacy reduction ranged from 2% to 7%.
The type of nozzle had a significant influence on the yield of maize cobs in 5 of 12 herbicide applications, and
spray volume significantly affected maize cob yield in 7 of 12 herbicide applications. In all statistically significant
cases, maize yield was higher when herbicides had been applied by standard nozzles (API, VMD 100–300 µm) at
300 l ha-1 spray volume. The highest yield reductions due to the use of AVI nozzles (7–11%) were determined in the
case of low volume sprays (150 l ha-1) consisting of big droplets (VMD more than 400 µm). Results suggest that
AVI nozzles can cause poor weed control only if used for applications of small spray volumes (less than 200 l ha-1)
with droplet VMD values larger than 400 µm, otherwise weed control results comparable to standard API nozzles
are achieved and the use of drift-reduction AVI nozzles does not result in maize yield reduction.
Key words: drift-reducing nozzles, Zea mays, weed control, 2,4-D, bentazon, foramsulfuron.
Introduction
Drift of agricultural sprays to adjacent nonagricultural areas (e.g., residential areas, water bodies,
sensitive nature conservation areas, etc.) is criticised
by the public and sanctioned by regulatory authorities
therefore farmers need to devote proper attention to drift
prevention. Drift of herbicides can cause high economic
losses, especially in the case of broad spectrum highly
systemic herbicides (glyphosate, 2,4-D, etc.), and direct
environmental pollution (e.g., poisoning of aquatic
organisms). The simplest method to avoid drift is to
spray in non-windy conditions and to increase the droplet
size, either by use of standard nozzles at low operating
pressure or by use of drift-reducing nozzles producing
large-size droplets.
The European Union (EU) directive on
sustainable use of pesticides (2009/128/EC; Directive...,
2009) obliges farmers and EU state authorities to find
advanced approaches for solving drift problems. In some
countries the use of drift-reducing nozzles is mandatory.
Farmers are obligated to use them when applying
herbicides in most agricultural areas. Sometimes farmers
oppose their use because they are not informed well on
drift-reduction spray technologies. The fear of reduced
coverage, and subsequently reduced weed control,
contributes to the reluctance to use low-drift nozzles.
It is well known that droplet size significantly affects
herbicide efficacy (Knoche, 1994; Matthews, 2000;
Ramsdale, Messersmith, 2001; Howarth, Holm, 2004;
Jensen, 2006). There is a lot of data available on the
effects of droplet size on herbicide efficacy, but in most
cases the results of field trials are not accompanied by
the data on related crop yield. Researchers studying the
effects of drift-reducing nozzles often conclude that these
nozzles provide the same level of weed control efficacy
as standard nozzles (Gehring et al., 2006; Nuyttens et al.,
2009). It was also demonstrated that certain combinations
of herbicides, nozzles and application parameters
(spray volume, droplet size, etc.) can lead to reduction
of herbicide efficacy against some weed species (Vajs,
Lešnik, 2005; Jensen, 2006; Brown et al., 2007; Sikkema
et al., 2008).
Our previous study (Lešnik et al., 2005)
suggested that the optimum nozzle type, water carrier
volume, and spray pressure are herbicide- and weed
species-specific. In the trials conducted in 2005, we
established that herbicide type and water volume for
372
The effects of drift-reducing nozzles on herbicide efficacy and maize (Zea mays L.) yield
herbicide application had a significant influence on the
yield of maize ears, whereas nozzle type on average did
not significantly influence the yield. In some trial plots,
drift-reducing nozzles caused significant yield losses.
Several years of research are needed to understand the
complex relationships among the key parameters of
herbicide application. As a result, we decided to perform
trials involving several seasons.
For herbicide application by drift-reducing
nozzles we are trying to find out the optimal balance
between herbicide efficacy and the rate of drift reduction.
This is especially important if we need to control mixed
weed populations consisting of perennial grasses and hard
to control annual and perennial broad-leaved weeds. This
situation is often present also on Lithuanian maize fields
(Auškalnienė, 2006; Auškalnienė, Auškalnis, 2007).
The aim of our study was to compare the efficacy
of weed control carried out with standard and with driftreducing nozzles and to relate the type of nozzles used
to maize yield. Our hypothesis was that application of
herbicides with drift-reducing nozzles does not cause
reduction of maize yield because of lower herbicide
efficacy.
Materials and methods
Experimental design and cropping technique.
Field trials were carried out at the experimental station of
the University of Maribor, Faculty of Agriculture and Life
Sciences (43°34′ N, 15°38′ E), Hoče, Slovenia during the
period of 2009–2011. Maize (Zea mays L.) was grown
according to the standard cropping technique (standard
ploughing and seedbed preparation, plant density 0.70 ×
0.15 m = 95.000 plants ha-1). The soil of the experimental
site is classified as Dystrict Cambisol (CMd) (World
reference base..., 2006) formed on diluvium with a pH
value of 5.98. The content of humus was 29 g kg-1. The
main nutrient composition was 150 mg kg-1 K2O and
97 mg kg-1 P2O5. Before pre-sowing tillage, complex
fertilisers were applied. The soil received 150 kg N,
40 kg P2O5 and 150 kg K2O per hectare.
Two trials were carried out each season at the
same location (200 meters apart). The trials were marked
as T1, T2, T3, T4, T5 and T6. Soil characteristics of
trial plots were very similar, only weed population
compositions were different. The proportion of grasses
and broad-leaved species in the total number (mass) of
weeds was different (Table 1). In season 2009 (T1 and
T2 trials) the maize hybrid LG22.44 (maturity class
FAO 320) was grown. The hybrid ‘Panda’ (maturity
class FAO 300) was grown in 2010 (T3 and T4) and
2011 (T5 and T6) (http://www.amacoint.com/en/
agriculture/seeds/corn/;
http://www.bc-institut.hr/
kukuruz_hr.htm). Classification of FAO maturity classes
was first published by Jugenheimer (1958). There was
no significant water shortage and summer weather
conditions facilitated fast maize development and yield
formation. Maize competitive ability against weeds was
high. All experiments included five replications in a
randomized block design. Plots were 4 m wide and 20 m
long. We had sixteen different treatments which were
combinations of four factors: nozzle type (API and AVI,
“Albuz”), spray volume (150 or 300 l ha-1), droplet size
(small droplets with a diameter of 100–300 µm, large
droplets with a diameter of 300–800 µm) and herbicide
mixture (2 mixtures). The information about technical
characteristics of API and AVI nozzles is available at
<http://www.albuz-spray.com/en/lituanie.html>.
The data were subjected to analysis of variance
(ANOVA). Tukey HSD test and t-test (P < 0.05) were
used for determining the significant differences between
treatment means. There was no need for transformation of
data on herbicide efficacy (%) and maize yield to assure
the homogeneity of data for analysis of variance. We also
had to control weed-free plots and plots which were not
treated with herbicides.
The weed population composition in trial plots
is presented in Table 1. Before application of herbicides,
the number of weeds per m2 of a specific species was
determined in the middle of each plot (randomly chosen
6 quadrates 0.25 × 0.25 m). On most of the chosen fields,
the weed flora was uniform in terms of species diversity,
only the share in total green mass among dominant species
was different in different experimental fields throughout
the seasons. Weeds were controlled only chemically, no
mechanical control measures were used.
Table 1. Weed population composition of trial plots on the day of herbicide application
Weed
ABUTH
AMBAR
AMARE
CHEAL
CONAR
ECHCG
ELYRE
FALCO
POLLA
Other
All together
NW T1
2009
135–150
25–50
100–130
30–50
1.3–2.7
20–35
20–35
10–15
35–50
30–40
480–600
NW T2
2009
150–200
60–80
185–230
140–170
2.2–3.0
40–60
30–50
30–40
35–50
20–30
430–590
NW T3
2010
30–45
20–35
100–130
70–90
3.5–6.5
160–250
10–15
20–50
70–90
40–50
400–550
NW T4
2010
10–14
20–25
80–95
40–85
1.1–2.2
120–160
45–75
10–30
40–65
30–50
380–480
NW T5
2011
170–190
10–35
60–75
130–150
3.7–5.2
160–190
60–95
20–35
70–90
40–60
380–500
NW T6
2011
130–150
5–15
80–120
60–90
4.0–8.2
70–110
40–55
15–20
45–60
40–70
450–570
Notes. ABUTH – Abutilon theophrasti Medik., AMBAR – Ambrosia artemisiifolia L., AMARE – Amaranthus retroflexus L.,
CHEAL – Chenopodium album L., CONAR – Convolvulus arvensis L., ECHCG – Echinochloa crus-galli (L.) Beauv. ELYRE –
Elytrigia repens (L.) Desv. ex Nevski, FALCO – Fallopia convolvulus (L.) A. Löwe, POLLA – Polygonum lapathifolium L., Other
– other weed species. NW – number of plants per m2; T1 – trial 1, T2 – trial 2, T3 – trial 3, etc.
ISSN 1392-3196
Žemdirbystė=Agriculture
The herbicide efficacy was assessed three times:
twice visually, 4 and 8 weeks after application by protocol
of chemical industry (BASF, Germany) (Bleiholder,
1989), and once by the assessment of fresh weed biomass
12 weeks after herbicide application. Only the data of the
third assessment are presented. In the middle of each plot
we randomly chose 6 quadrates by throwing a metal frame
(0.5 m × 0.5 m). Weeds found within each quadrate were
cut to the ground, separated by species and fresh mass
was weighed. The efficacy of herbicide was expressed as
relative reduction (%) in weed biomass in comparison to
the biomass of weeds in untreated plots. The assessment
was done for each weed species separately, but in this
paper we present only average data for all species together
(total biomass of all species together). Maize yield was
determined by manually collecting fresh cobs (ears) from
plants developing on the 10 m2 area in the middle of plots
(3 middle rows × 5 m).
Application technique and herbicides applied.
In each trial, two herbicide mixtures were studied
(foramsulfuron 50 g ha-1 + bentazon 850 g ha-1 and
foramsulfuron 50 g ha-1 + 2,4-D 750 g ha-1). Both mixtures
were applied at two spray volumes (150 or 300 l ha-1) with
two types of nozzles (API and AVI) producing small or big
droplets. Each trial included 80 plots (2 × 2 × 2 × 2 × 5 =
80) and several control plots (no weed control and weedfree control plots). Bentazon (Basagran 480, BASF) was
chosen as a contact herbicide, and foramsulfuron (Equip,
“Bayer”, Germany) and 2,4-D (Herbocid, “Nufarm”,
Austria) as systemic herbicides. These three herbicides
Vol. 99, No. 4 (2012)
373
are frequently used by Slovenian farmers. They have
different modes of action and translocation which
enables testing the interaction between nozzle type and
type of herbicide (systemic or contact). Both herbicide
mixtures control a very broad spectrum of weeds (grasses
and dicots, annuals and perennials). That enabled us to
exclude the effects of individual weed species which
were not completely controlled by a specific herbicide
and could therefore prevail in the weed population.
According to our previous trials, the effects of such weed
species can mask the effects of trial treatments (nozzle
type, spray volume, etc.).
All three herbicides were applied at 90% of full
recommended rates. In all three seasons, the herbicides
were applied within the period from May 15 to 25,
when maize plants had 3 to 4 leaves and the majority of
weeds had 2 to 5 leaves. Herbicides were applied after
the emergence of the majority of weeds. The studied
herbicides did not have any residual activity in the soil.
The herbicides were applied with a standard
tractor mounted field boom sprayer (“Agromehanika
AGS 600E-SD”, Slovenia) set to deliver 150 or 300 l of
spray per hectare. Technical parameters of applications
are presented in Table 2. API nozzle is a standard 110
degree flat fan nozzle for the spray applications in field
crops, and AVI is a drift-reducing air-inclusion nozzle
with the same jet characteristics. Nozzle volume median
diameter (VMD) values corresponding to the operating
pressure were provided by nozzle producer “Albuz”
(“Saint-Gobain”, France).
Table 2. Technical parameters of applications
Nozzle type
Operating
pressure
kPa
Nozzle
output
l min-1
Tractor
speed
km h-1
Spray
volume
l ha-1
Droplet
VMD*
50 μm
No. imp.
WSP**
API 110-02
API 110-03
AVI 110-02
AVI 110-03
API 110-03
API 110-04
AVI 110-03
AVI 110-04
350 ± 20
160 ± 20
350 ± 20
160 ± 20
620 ± 20
350 ± 20
620 ± 20
350 ± 20
0.86 ± 0.05
0.86 ± 0.05
0.86 ± 0.05
0.86 ± 0.05
1.73 ± 0.05
1.73 ± 0.05
1.73 ± 0.05
1.73 ± 0.05
7 ± 0.15
7 ± 0.15
7 ± 0.15
7 ± 0.15
7 ± 0.15
7 ± 0.15
7 ± 0.15
7 ± 0.15
150 ± 10
150 ± 10
150 ± 10
150 ± 10
300 ± 10
300 ± 10
300 ± 10
300 ± 10
128 ± 10
212 ± 10
445 ± 15
730 ± 20
125 ± 20
215 ± 20
375 ± 20
565 ± 15
85–115
40–95
40–75
25–50
80–120
55–95
40–65
35–75
Note. * – volume median diameter, ** – number of droplet impacts per cm2 measured by “Optomax” droplet scorer on water
sensitive paper deposited on soil surface at the distance of 90 cm from the nozzle.
Results and discussion
Efficacy of weed control and maize yield in
the season of 2009. The data on herbicide efficacy and
maize yield from trials T1 and T2 are shown in Tables 3
and 4. In T1 trial, standard API nozzle provided higher
herbicide efficacy than AVI nozzle for both herbicide
mixtures (F + B and F + D).
The use of AVI nozzles resulted in 7.4% maize
yield reduction (2.12 vs. 2.29 kg m-2) in the case of
mixture of foramsulfuron and 2,4-D in comparison to the
plots sprayed with API nozzles (Table 4). The reduction of
yield caused by application of mixture of foramsulfuron
and bentazon (2.16 vs. 2.24 kg m-2) was not statistically
significant. We think that the main reason could be high
population of velvetleaf (Abutilon theophrasti, 135–150
m-2). The reduction of efficacy due to the use of AVI nozzles
was higher when we used 2,4-D, compared to bentazon
applied with the same nozzles. 2,4-D had lower efficacy
against velvetleaf than bentazon (Table 3). The established
efficacy resulted from foramsulfuron action but not from
that of 2,4-D. The increase of droplet size can additionally
decrease the efficacy of 2,4-D against velvetleaf (Knoche,
1994; Wolf, 2000). Higher spray volume increased the
average herbicide efficacy and consequently also the
maize yield at both herbicide mixtures. The population
of grasses (Echinochloa crus-galii and Elytrigia repens)
was moderate and foramsulfuron performed well. The
efficacy of the control of quackgrass (E. repens) was
reduced by 10% when we delivered 150 l of spray per
hectare by AVI 110-03 and AVI 110-02 nozzles. In T2
trial, we had a huge population of velvetleaf (150–200
m-2), pigweed (Amaranthus retroflexus, 185–230 m-2) and
lambsquarters (Chenopodium album, 140–170 m-2). API
nozzles provided slightly higher efficacy than AVI nozzles
for both herbicide mixtures, but these differences did not
result in significant difference in maize yield (Table 4).
374
The effects of drift-reducing nozzles on herbicide efficacy and maize (Zea mays L.) yield
Table 3. The efficacy of herbicide combinations against individual weed species as influenced by the nozzle type (API
and AVI) and spray volume (l ha-1) for trials T1 and T2 in 2009
Weed
F+B
API
F+B
AVI
ABUTH
AMBAR
AMARE
CHEAL
CONAR
ECHCG
ELYRE
FALCO
POLLA
Average
97.3 b
96.5 a
99.3 a
99.2 a
85.3 b
96.4 b
93.7 b
96.9 b
97.6 b
95.8 B
95.3 a
95.6 a
99.1 a
99.7 a
79.3 a
88.7 a
81.1 a
93.7 a
93.7 a
91.8 A
ABUTH
AMBAR
AMARE
CHEAL
CONAR
ECHCG
ELYRE
FALCO
POLLA
Average
95.3 a
93.3 a
98.4 a
97.2 a
81.3 b
94.1 b
90.1 b
88.1 b
91.1 b
92.1 B
92.3 a
94.1 a
99.2 a
97.4 a
75.2 a
90.1 a
85.5 a
83.1 a
87.7 a
89.4 A
F+B
F+B
150
300
Trial T1, season 2009
90.4 a
96.4 b
87.7 a
96.2 b
97.6 a
99.7 a
98.3 a
99.5 a
79.3 a
87.1 b
95.7 a
94.7 a
94.8 a
93.1 a
95.3 a
95.4 a
91.6 a
94.7 b
92.3 A
95.2 B
Trial T2, season 2009
91.7 a
94.3 b
84.3 a
90.1 b
95.5 a
98.5 b
93.4 a
96.5 b
72.4 a
80.3 b
95.3 a
92.3 a
92.8 b
85.5 a
92.6 a
95.1 a
89.3 a
93.6 b
89.7 A
91.8 B
F+D
API
F+D
AVI
F+D
150
F+D
300
92.3 b
96.5 a
97.4 a
98.2 a
91.3 a
96.1 b
89.5 b
96.9 a
98.6 a
95.2 B
85.4 a
93.5 a
99.8 a
99.1 a
95.7 b
89.5 a
83.1 a
97.4 a
97.1 a
93.4 A
84.0 a
87.3 a
94.9 a
95.1 a
90.3 a
97.1 a
91.7 a
92.9 a
94.7 a
92.0 A
89.3 b
96.0 b
99.5 b
99.1 b
96.9 b
97.4 a
92.0 a
99.7 b
99.5 b
96.6 B
82.4 a
93.9 a
97.9 a
97.5 a
89.3 a
94.1 b
83.3 b
92.1 a
92.1 a
91.4 B
92.0 b
91.6 a
99.5 a
96.4 a
95.3 b
80.1 a
70.5 a
92.1 a
90.7 a
89.8 A
90.1 a
91.3 a
95.7 a
94.4 a
61.9 a
96.1 a
90.4 b
88.6 a
85.3 a
88.2 A
95.3 b
92.7 a
99.5 a
95.5 a
87.7 b
93.3 a
84.7 a
95.8 b
93.4 b
93.1 B
Notes. Values marked with the same letter within individual weed species and individual trial factor (nozzle API vs. AVI or spray
volume 150 vs. 300) do not differ significantly according to the t-test (P < 0.05, n = 20). F + B – foramusulfuron 60 g ha-1 +
bentazon 850 g ha-1, F + D – foramsulfuron 60 g ha-1 + 2,4-D 750 g ha-1.
Table 4. Herbicide efficacy and maize yield in the trials (T1 and T2) of the 2009 season as influenced by the nozzle
type (API and AVI), spray volume, droplet volume median diameter (VMD) and herbicide mixture
T1 (F + B)
T1 (F + D)
T2 (F + B)
T2 (F + D)
Nozzle, spray
volume, VMD
Eff.
Y
Eff.
Y
Eff.
Y
Eff.
Y
API, 150, 128
API, 150, 212
94.5 cd
95.6 cd
2.17 b
2.19 b
92.7 b
93.6 bc
2.27 ab
2.30 ab
92.5 cd
92.7 cd
2.14 a
2.07 a
90.7 bcd
90.3 bc
2.05 a
2.15 ab
AVI, 150, 445
90.8 ab
2.07 a
93.7 bc
2.11 ab
88.7 b
1.89 a
87.8 b
1.99 a
AVI, 150, 730
88.4 a
2.05 a
87.9 a
1.95 a
84.6 a
1.90 a
83.9 a
1.94 a
API, 300, 125
96.7 d
2.20 b
94.8 bc
2.20 ab
90.4 bc
2.02 a
90.8 bcd
2.02 a
API, 300, 215
96.3 d
2.38 d
99.7 c
2.38 b
92.5 cd
2.07 a
93.9 de
2.15 ab
AVI, 300, 375
AVI, 300, 565
95.6 cd
92.3 bc
2.30 c
2.20 b
96.7 cd
95.3 bc
2.25 ab
2.18 ab
93.7 d
90.5 bc
2.09 a
2.12 a
95.9 e
91.7 ed
2.27 b
2.02 a
150 l ha-1
300 l ha-1
92.3 A
95.2 B
2.12 A
2.27 B
92.0 A
96.6 B
2.16 A
2.25 B
89.7 A
91.8 B
2.00 A
2.07 A
88.2 A
93.1 B
2.03 A
2.11 A
API
AVI
95.8 B
91.8 A
2.24 A
2.16 A
95.2 B
93.4 A
2.29 B
2.12 A
92.1 B
89.4 A
2.07 A
2.00 A
91.4 B
89.8 A
2.09 A
2.05 A
Notes. Means marked with the same small letters do not differ significantly according to the Tukey HSD test (P < 0.05, n = 5)
and means marked with capital letters do not differ significantly according to the t-test (P < 0.05, n = 20). Bold numbers indicate
statistically significant differences between F + B and F + D herbicide mixtures according to the t-test (P < 0.05, n = 5 or 20). F +
B – foramusulfuron 60 g ha-1 + bentazon 850 g ha-1, F + D – foramsulfuron 60 g ha-1 + 2,4-D 750 g ha-1. VMD small – 125, 128,
212, 215 µm, big – 375, 445, 565, 730 µm. Eff. – efficacy %, Y – kg of fresh cobs m-2.
Pigweed and lambsquarters control was equally
successful with API and AVI nozzles (T1 and T2) (Table
3). In treatments T1 (F + B), T2 (F + B) and T2 (F +
D), the differences in maize yield were not significant.
In only one of four herbicide applications the use of AVI
nozzles resulted in yield reduction, when compared to
API nozzles. The results from the season 2009 suggest
that the use of drift-reducing AVI nozzles did not result
in significant maize yield reduction, compared to those
achieved by API nozzles.
ISSN 1392-3196
Žemdirbystė=Agriculture
Efficacy of weed control and maize yield in the
season of 2010. The data on herbicide efficacy and maize
yield from trials T3 and T4 are shown in Tables 5 and 6.
Weed population had a different structure than in 2009. The
most frequent weeds were barnyard grass (Echinochloa
crus-galii, 120–250 m-2), pigweed (Amaranthus
retroflexus) and knotweeds (Polygonum lapathifolium
and Fallopia convolvulus). Both knotweeds played an
Vol. 99, No. 4 (2012)
375
important role in maize yield reduction because none of
the three herbicides applied gave efficient control of the
two species. In the autumn, the populations of these two
species were abundant. In T3 trial, higher spray volume
increased herbicide efficacy and API nozzles provided
higher efficacy of weed control than AVI nozzles for both
herbicide mixtures F + B and F + D (Table 5).
Table 5. The efficacy of herbicide combinations against individual weed species as influenced by the nozzle type (API
and AVI) and spray volume (l ha-1) for trials T3 and T4 in 2010
Weed
F+B
API
F+B
AVI
ABUTH
AMBAR
AMARE
CHEAL
CONAR
ECHCG
ELYRE
FALCO
POLLA
Average
96.3 a
93.9 a
98.8 a
98.2 a
83.1 a
94.7 b
90.9 b
90.6 a
92.3 b
93.2 B
93.8 a
90.5 a
98.1 a
97.1 a
84.2 a
80.4 a
72.3 a
91.4 a
88.7 a
88.5 A
ABUTH
AMBAR
AMARE
CHEAL
CONAR
ECHCG
ELYRE
FALCO
POLLA
Average
94.8 a
92.3 a
98.3 a
97.7 a
84.2 a
93.5 b
90.3 b
90.7 a
88.9 a
92.3 A
95.5 a
96.3 b
98.1 a
98.4 a
83.7 a
87.5 a
83.5 a
94.5 b
93.2 b
92.3 A
F+B
F+B
150
300
Trial T3, season 2010
90.7 a
95.3 b
86.5 a
88.1 a
93.5 a
98.1 b
95.8 a
98.2 a
71.8 a
83.7 b
95.3 a
92.5 a
92.8 b
87.3 a
89.9 a
95.2 b
87.4 a
94.1 b
89.3 A
92.5 B
Trial T4, season 2010
90.5 a
95.3 b
87.1 a
94.1 b
97.5 a
98.9 a
97.4 a
98.4 a
76.5 a
89.8 b
94.5 b
90.7 a
90.8 a
88.7 a
91.6 a
95.7 b
89.5 a
94.4 b
90.6 A
94.0 B
F+D
API
F+D
AVI
F+D
150
F+D
300
89.1 a
96.2 a
99.3 a
99.8 a
93.1 a
95.1 b
92.4 b
94.5 a
97.3 b
95.2 B
90.7 a
92.5 a
99.1 a
97.2 a
95.5 a
87.8 a
81.8 a
95.7 a
94.9 a
92.8 A
88.8 a
89.8 a
96.3 a
98.9 a
86.1 a
96.6 b
93.5 b
94.7 a
92.3 a
93.0 A
94.4 b
95.3 b
99.6 a
97.3 a
93.3 b
92.3 a
88.3 a
98.1 a
96.4 b
95.0 B
84.7 a
90.3 a
98.9 a
98.5 a
91.1 a
94.6 b
89.9 b
95.7 a
96.9 a
93.4 A
88.6 a
92.2 a
99.4 a
98.2 a
95.6 b
83.6 a
77.8 a
96.5 a
96.1 a
92.0 A
80.4 a
81.5 a
93.6 a
96.2 a
86.2 a
97.8 b
93.6 b
92.1 a
92.2 a
90.4 A
92.8 b
95.8 b
99.5 b
98.9 a
95.2 b
91.5 a
89.5 a
94.9 a
96.9 b
95.0 B
Note. Explanations under Tables 1 and 3.
The same is true for T4 trial. In F + B mixture
of T3 trial this resulted in significant differences in maize
yield (API 2.06 and AVI 1.85 kg m-2) but in F + D mixture
the differences in yield were not significant (API 2.15
and AVI 2.11 kg m-2) (Table 6).
The efficacy of foramsulfuron for control of
barnyard grass was reduced by more than 15% and
in quackgrass by more than 10% when applied by
AVI nozzles in both T3 and T4 trials (Table 6). The
performance of API and AVI nozzles in terms of herbicide
efficacy in T4 trial was totally comparable; as a result, the
maize yields at both spray mixtures were not statistically
different either. Based on the results from the 2010 season,
we can conclude that the use of drift-reducing nozzles
provides the same level of weed control and maize yield
as standard nozzles. For grass control it is well known
that better results can be achieved by using low spray
volumes and smaller droplets, which have better adhesion
and retention capacity (Knoche, 1994; Vajs, Lešnik, 2005;
Brown et al., 2007). In our trial, it was demonstrated that
drift-reducing nozzles should not be used for low volume
applications because the efficacy of grass control could be
reduced significantly. This is because of too low droplet
density and droplet retention on grass surface.
In Table 2, when we compare AVI 110-03 at
160 kPa pressure (25–50 impacts) with API 110-03 at the
same pressure (40–95 impacts), it is possible to notice
the differences in the number of droplet impacts per
cm2. These differences in density of droplet impacts are
important for small emerging barnyard grass plants. At
25 impacts per cm2, many small emerging plants are not
hit by droplets and consequently the amount of herbicide
transposed to weed tissue is too low for achieving high
efficacy. These results are consistent with those obtained
by Ramsdale and Messersmith (2001) and by Brown et al.
(2007). They demonstrated that the control of barnyard
grass by the application of herbicide with drift-reducing
nozzles can be improved by the increased operating
pressure.
There are also other options to improve the
efficacy of herbicides for grass control. The first is
addition of adjuvant (McMullan et al., 2006) and the
second is use of nozzles with non-vertical orientation
(Jensen, 2010). Adjuvants can alter herbicide-nozzle
interaction. McMullan et al. (2006) demonstrated the
effects of adjuvants on foramulfuron efficacy. The
efficacy of foramsulfuron was decreased by 30% when
applied with air-induction nozzles without adjuvant,
compared to that achieved with standard nozzles. When
adjuvant was added the efficacy of foramsulfuron applied
with air-induction nozzles was increased by 40%,
compared to that achieved with standard nozzles. Jensen
(2010) established that the efficacy of herbicides applied
with standard and drift-reducing nozzles for grass control
could be increased by angling the spray either forward
or backward, relative to the direction of travelling. The
highest improvement in the efficacy was obtained using
a 60° forward-angled spray.
376
The effects of drift-reducing nozzles on herbicide efficacy and maize (Zea mays L.) yield
Table 6. Herbicide efficacy and maize yield in the trials (T1 and T2) of the 2010 season as influenced by the nozzle
type (API and AVI), spray volume, droplet volume median diameter (VMD) and herbicide mixture
Nozzle, spray
volume, VMD
API, 150, 128
API, 150, 212
AVI, 150, 445
AVI, 150, 730
API, 300, 125
API, 300, 215
AVI, 300, 375
AVI, 300, 565
150 l ha-1
300 l ha-1
API
AVI
T3 (F + B)
Eff.
Y
92.5 b
2.09 a
93.4 b
2.05 a
88.8 ab
1.80 a
82.4 a
1.66 a
93.7 b
2.04 a
93.3 b
2.06 a
92.6 b
2.05 a
90.3 b
1.90 a
89.3 A
1.90 A
92.5 B
2.01 B
93.2 B
2.06 B
88.5 A
1.85 A
T3 (F + D)
Eff.
Y
93.7 ab
2.17 ab
95.1 c
2.23 b
93.7 ab
2.18 ab
89.5 a
1.99 a
96.8 c
2.02 a
95.3 c
2.16 ab
95.7 c
2.20 ab
92.3 ab
2.08 a
93.0 A
2.14 A
95.0 B
2.12 A
95.2 B
2.15 A
92.8 A
2.11 A
T4 (F + B)
Eff.
Y
91,5 ab
2.04 a
91.7 ab
2.09 a
90.7 ab
2.01 a
88.4 a
1.96 a
92.4 c
2.02 a
93.5 c
2.17 a
96.7 d
2.19 a
93.3 c
2.12 a
90.6 A
2.02 A
94.0 B
2.12 B
92.3 A
2.08 A
92.3 A
2.07 A
T4 (F + D)
Eff.
Y
91.7 bc
2.15 ab
92.3 bc
2.18 ab
89.8 ab
2.07 a
87.9 a
1.99 a
93.8 cd
2.22 ab
95.9 d
2.18 ab
96.5 d
2.25 b
93.7 cd
2.22 ab
90.4 A
2.09 A
95.0 B
2.21 B
93.4 A
2.18 A
92.0 A
2.13 A
Note. Explanations under Table 4.
The efficacy of weed control and maize yield
in the season of 2011. Results for the 2011 season are
presented in Tables 7 and 8. The weed population of
trial plots in 2011 was larger than in 2010. We had a
large population of velvetleaf (Abutilon theophrasti),
barnyard grass (Echinochloa crus-galii), quackgrass
(Elytrigia repens) and bindweed (Convolvulus arvensis,
3 to 8 m-2). Especially the last two weed species had an
important influence on the yield loss. At the end of the
season we found dense stands of Elytrigia and Abutilon
on many plots. In T5 trial, the use of AVI nozzles resulted
in yield reduction for both herbicide mixtures (F + B,
API-2.33/AVI-2.26 kg m-2 and F + D, API-2.30/AVI2.15 kg m-2) (Table 8). In T6 trial, AVI nozzles had worse
performance only for F + B mixture. When we applied
F + D mixture, both nozzles provided the same level
of efficacy and maize yield. In plots of T6 trial, there
were large populations of bindweed (C. arvensis) and
black bindweed (Fallopia convolvulus). We noticed that
increased spray volume and partially also bigger droplet
size increased the efficacy of bentzone and 2,4-D against
bindweed and partially against bindweed (FALCO, API
(F + B) = 89.3% vs. AVI (F + B) = 94.9%) (Table 7). The
difference among bindweed and other weed species could
be noticed. The highest herbicide efficacy was achieved
with higher spray volume and with medium-size droplets
(API 110-04, 300, VMD 215 and AVI 110-03, 300, VMD
375). This demonstrates that the response of bindweed
to the application technique is not the same as in annual
broad-leaved species and grasses (e.g., T5, CONAR,
Table 7. The efficacy of herbicide combinations against individual weed species as influenced by the nozzle type (API
and AVI) and spray volume (l ha-1) for trials T5 an T6 in 2011
Weed
F+B
API
F+B
AVI
ABUTH
AMBAR
AMARE
CHEAL
CONAR
ECHCG
ELYRE
FALCO
POLLA
Average
96.1 a
95.2 a
97.9 a
98.5 a
87.1 a
97.5 b
92.4 b
89.3 a
92.0 a
94.0 A
95.9 a
96.7 a
98.9 a
98.8 a
89.7 a
83.5 a
80.5 a
94.9 b
93.6 a
92.5 A
ABUTH
97.4 a
94.7 a
AMBAR
97.7 a
93.3 a
AMARE
99.1 a
98.5 a
CHEAL
99.1 a
98.6 a
CONAR
88.6 a
89.7 a
ECHCG
95.5 b
83.5 a
ELYRE
91.3 b
81.0 a
FALCO
91.0 a
93.7 a
POLLA
93.4 a
93.2 a
94.8 B
91.8 A
Average
Note. Explanations under Tables 1 and 3.
F+B
F+B
150
300
Trial T5, season 2011
90.3 a
94.2 b
93.6 a
95.2 a
98.5 a
98.6 a
97.5 a
98.1 a
79.4 a
93.3 b
95.5 b
90.1 a
94.8 b
87.5 a
90.6 a
96.7 b
90.5 a
94.1 b
92.3 A
94.2 A
Trial T6, season 2011
94.4 a
92.0 a
94.1 a
94.6 a
98.0 a
98.3 a
97.9 a
95.1 a
89.9 a
90.5 a
96.6 b
90.0 a
93.8 b
87.1 a
88.1 a
92.7 b
94.1 a
93.3 a
94.1 B
92.6 A
F+D
API
F+D
AVI
F+D
150
F+D
300
82.2 a
93.9 a
99.5 a
99.3 a
91.4 a
93.5 b
89.7 b
95.9 a
96.1 a
93.5 B
89.9 b
95.6 a
99.3 a
99.2 a
96.6 b
80.5 a
79.5 a
96.1 a
96.7 a
92.6 A
83.0 a
90.0 a
97.6 a
98.2 a
86.2 a
96.5 b
90.5 b
87.0 a
94.5 a
91.5 A
94.4 b
96.0 b
99.0 a
98.9 a
96.1 b
90.0 a
87.0 a
94.1 b
95.0 a
94.5 B
83.6 a
94.0 a
99.3 a
98.2 a
91.5 a
94.9 b
90.8 b
95.9 a
96.9 a
93.9 A
84.0 a
95.9 a
99.2 a
99.7 a
96.7 b
85.0 a
84.6 a
96.9 a
96.9 a
93.2 A
84.3 a
92.5 a
96.6 a
97.1 a
86.2 a
96.1 a
92.0 a
90.5 a
93.6 a
92.1 A
94.0 b
95.9 b
99.1 a
98.8 a
96.5 b
91.6 a
89.2 a
94.4 b
95.5 a
95.0 B
ISSN 1392-3196
Žemdirbystė=Agriculture
F + B 150 (79.4%) vs. F + B 300 (93.3%) (Table 7).
Nozzles and spray volumes had no significant effect on
Vol. 99, No. 4 (2012)
377
herbicide efficacy for the control of pigweed, ragweed
and lambsquarters.
Table 8. Herbicide efficacy and maize yield in the trials (T1 and T2) of the 2011 season as influenced by the nozzle
type (API and AVI), spray volume, droplet volume median diameter (VMD) and herbicide mixture
Nozzle, spray
volume, VMD
API, 150, 128
API, 150, 212
AVI, 150, 445
AVI, 150, 730
API, 300, 125
API, 300, 215
AVI, 300, 375
AVI, 300, 565
150 l ha-1
300 l ha-1
API
AVI
T5 (F + B)
Eff.
Y
91.5 ab
2.19 a
94.4 b
2.28 ab
90.8 a
2.17 a
92.4 ab
2.21 ab
94.7 ab
2.40 ab
93.5 ab
2.46 b
93.6 ab
2.25 ab
93.3 ab
2.40 ab
92.3 A
2.21 A
94.2 A
2.38 B
94.0 A
2.33 B
92.5 A
2.26 A
T5 (F + D)
Eff.
Y
90.7 a
2.27 ab
92.1 ab
2.13 ab
90.5 a
2.07 a
90.5 a
2.15 ab
94.8 ab
2.32 ab
96.3 b
2.46 b
93.7 ab
2.20 ab
93.3 ab
2.18 ab
91.5 A
2.16 A
94.5 B
2.29 B
93.5 B
2.30 B
92.6 A
2.15 A
T6 (F + B)
Eff.
Y
96.5 b
2.34 b
95.7 b
2.39 b
93.7 ab
2.21 ab
90.4 a
1.92 a
93.4 ab
2.27 ab
93.8 ab
2.37 b
92.7 ab
2.19 ab
90.3 a
2.03 a
94.1 B
2.21 A
92.6 A
2,21 A
94.9 B
2.34 B
91.8 A
2.08 A
T6 (F + D)
Eff.
Y
92.7 ab
2.35 a
93.1 ab
2.28 a
91.8 ab
2.17 a
90.9 a
1.93 a
94.8 ab
2.12 a
94.9 ab
2.28 a
95.5 b
2.45 a
94.7 ab
2.32 a
92.1 A
2.18 A
95.0 B
2.29 A
93.9 A
2.25 A
93.2 A
2.21 A
Note. Explanations under Table 4.
The difference between F + B and F + D mixture
in T6 trial in terms of nozzle effect on yield lies in lower
efficacy of bentazon against knotweed than 2,4-D and in
higher population of barnyard grass and quackgrass in F +
B plots. The season of 2011 revealed the whole complexity
of nozzle-herbicide-weed species interactions and their
impact on maize yield. In 3 of 4 herbicide applications, the
use of AVI nozzles resulted in yield reduction, compared to
API nozzles. The yield reduction ranged from 5% to 10%.
This rate of yield reduction cannot be ignored. The results
obtained in the season 2011 differed from the results of the
seasons 2009 and 2010. Sikkema et al. (2008) established
almost the same level of yield reduction in soybean when
comparing standard and drift-reducing nozzles used for
the control of very similar weed populations. In several
trials, the use of drift-reducing nozzles, compared with the
standard nozzles for bentazon application, decreased the
soybean yield by 7%. The decrease of bentazon efficacy
applied in a form of big droplets was noted by Prokop
and Veverka (2003). They tested the effect of six different
droplet sizes (VMD 183 to 911 μm) of bentazon spray in
order to control Chenopodium album L. The efficiency
significantly increased with smaller droplet sizes. The
lowest efficacy was achieved by the droplet spectra of
586 and 911 μm.
Conclusions
1. The results of our trials showed that the
response of different weed species to herbicide application
parameters was not uniform and was also dependent on
herbicide type (contact or systemic). Quite different
effects of nozzles in different seasons were observed
despite application of the same herbicide mixtures to the
same weed populations in the same fields.
2. Nozzles and spray volume did not have any
significant effect on the efficacy of the tested herbicide
mixtures of foramsulfuron + bentazon or 2,4-D in the
control of pigweed, ragweed and lambsquarters.
3. Bigger droplets and higher spray volume
decreased the efficacy of the tested herbicide mixtures
against grass weeds (quackgrass and barnyard grass) and
increased the efficacy against velvetleaf, bindweed and
knotweed.
4. In the case of moderate weed population with
an equal ratio of grasses to broad-leaved weeds, the use
of drift-reducing nozzles did not lead to such a decrease
of herbicide efficacy which could cause a significant
maize yield reduction.
5. Our investigation showed that there were many
interactive effects which influenced herbicide efficacy.
For a successful application of herbicides and at the same
time the reduction of their drift, farmers need to develop
nozzle selection skills. They must know how to select the
most appropriate nozzles and corresponding application
parameters – flow rates, pressures, droplet sizes (volume
median diameter, VMD) – for specific combinations of
weeds species and types of herbicides. Our study suggests
that the mandatory use of drift-reducing nozzles can be
a successful measure for herbicide drift reduction only
when farmers are capable of balancing all the discussed
aspects of nozzle and herbicide selection.
Received 17 05 2012
Accepted 22 10 2012
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Žemdirbystė=Agriculture, vol. 99, No. 4 (2012), p. 371–378
UDK 633.15:631.348.45
Purkštukų tipo įtaka herbicidų efektyvumui ir
paprastojo kukurūzo (Zea mays L.) derliui
M. Lešnik, B. Kramberger, S. Vajs
Maribor universitetas, Slovėnija
Santrauka
Siekiant palyginti herbicidų efektyvumą paprastojo kukurūzo (Zea mays L.) pasėliui, lauko bandymai vykdyti
2009–2011 m. Herbicidai purkšti standartiniais (API, “Albuz”) ir specialiais (AVI, “Albuz”) purkštukais,
mažinančiais lašelių nunešimą pavėjui. Herbicidų mišiniai, sudaryti iš 2,4-D, bentazono ir foramsulfurono, purkšti
pasėliui sudygus, naudojant pakabinamą lauko purkštuvą, 150 ir 300 l tirpalo hektarui. Išpurškiamo tirpalo lašeliai
skyrėsi dydžiu, jų tūrio medianinis skersmuo buvo nuo 100 iki 800 µm. Bandymų pagrindinės piktžolių rūšys buvo
Ambrosia artemisiifolia, Amaranthus retroflexus, Chenopodium album, Convolvulus arvensis, Elytrigia repens,
Echinochloa crus-galii, Polygonum lapathifolium ir Fallopia convolvulus. Vertintas herbicidų efektyvumas (%)
ir kukurūzų derlius. Nustatyta skirtinga tirtų veiksnių įtaka herbicidų efektyvumui plačialapėms ir siauralapėms
piktžolėms. Palyginus su standartiniais API purkštukais, AVI purkštukų, mažinančių lašelių nunešimą pavėjui,
efektyvumas buvo mažesnis 8 iš 12 herbicidų purškimo atvejų. Efektyvumo sumažėjimas svyravo nuo 2 iki 7
%. Kukurūzų burbuolių derliui reikšmingą įtaką purkštuko tipas turėjo 5 iš 12, o purškiamo tirpalo norma – 7
iš 12 herbicidų purškimo atvejų. Visais atvejais kukurūzų derlius iš esmės didesnis buvo herbicidus išpurškus
standartiniais purkštukais (API, tūrio medianinis skersmuo – 100–300 µm), 300 l ha-1 tirpalo. Didžiausias derliaus
sumažėjimas (7–11 %) naudojant AVI purkštukus nustatytas purškiant mažą (150 l ha-1) normą dideliais lašeliais
(tūrio medianinis skersmuo didesnis nei 400 µm). Tyrimo rezultatai parodė, kad purškiant AVI purkštukais gaunama
prasta piktžolių kontrolė, jeigu purškiama maža (mažiau nei 200 l ha-1) norma tirpalo, tūrio medianinio skersmens
vertėms esant didesnėms nei 400 µm. Kitais atvejais piktžolių kontrolė yra panaši į gaunamą naudojant API
purkštukus, o AVI purkštukų, mažinančių lašelių nunešimą pavėjui, naudojimas kukurūzų derliaus nesumažina.
Reikšminiai žodžiai: purkštukai, mažinantys lašelių nunešimą pavėjui, Zea mays, piktžolių kontrolė, 2,4-D,
bentazonas, foramsulfuronas.